This project involves digital processing and computer interpretation in electrocardiography (ECG), which is the most widely used diagnostic and prognostic tool in cardiovascular disease including ECG monitors, ambulatory ECGs, signal-averaged ECGs, and exercise ECGs. In the U.S. up to 150 million routine diagnostic ECGs are performed annually. The ambulatory ECG and the signal-averaged ECG are used to estimate risk of sudden death from fatal cardiac rhythm disturbances. The exercise ECG is used to diagnose coronary disease. The National Heart, Lung, and Blood Institute (NHLBI) proposed the creation of a national archive of ECG databases from epidemiological studies and clinical trials conducted by public and academic medical centers, especially those funded by NHLBI. The ultimate goal of this archive would be raw digital ECG data and ancillary information (demographics, disease status, etc.) accessible by clinical investigators and epidemiologists over a high speed data link. As a first step, MSCL set up and currently maintains a public ECG Registry on a NHLBI website, where investigators can post their database or find out what's available and who to contact. A particularly useful application of ECG is the determination heart rate variability (HRV), an index of autonomic nervous system influence upon the heart. Also in FY01, a follow-up study in the long term collaboration with Children's National Medical Center of HRV in syncopal patients is in preparation. In collaboration with NHLBI; the Agency for Health Care Policy and Research; and the Minnesota Heart Institute Foundation a meta-analysis of data for different diagnostic modalities such as HRV, signal-average ECGs, frequent ventricular beats and ejection fraction has been performed to compare their prognostic power after myocardial infarction; the manuscript is in press. In collaboration with several members of previous AHA Committees on electrocardiography, a report re-establishing AHA electrical safety standards for electrocardio-graphs has been published. J. Bailey chairs the ECG Committee for the Association for Advancement of Medical Instrumentation supervising six working groups (subcommittees) dealing with national and international medical device standards. Four standards documents were approved by the American National Standards Institute, two of which were already published last year and two more this year.